slideshow/source/inc/activity.hxx

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  19
  20 #ifndef INCLUDED_SLIDESHOW_SOURCE_INC_ACTIVITY_HXX
  21 #define INCLUDED_SLIDESHOW_SOURCE_INC_ACTIVITY_HXX
  22
  23 #include <memory>
  24
  25 #include "disposable.hxx"
  26
  27
  28 /* Definition of Activity interface */
  29
  30 namespace slideshow::internal
  31     {
  32
  33         class Activity : public Disposable, public virtual SharedPtrAble
  34         {
  35         public:
  36             /** Perform the activity associated with this interface's
  37                 implementation.
  38
  39                 @return true, if activity continues, or false, if activity has
  40                 ended.
  41             */
  42             virtual bool perform() = 0;
  43
  44             /** Calculates whether the activity lags time.
  45
  46                 If this method returns a time lag greater than 0.0,
  47                 the ActivitiesQueue will adjust the global slideshow
  48                 time, by subtracting the given amount of lag.
  49
  50                 @return time lag or 0.0. Value must be greater or
  51                 equal than zero.
  52             */
  53             virtual double calcTimeLag() const = 0;
  54
  55             /** Query whether this activity is still continuing
  56
  57                 @return true, if this activity still
  58                 continues. Returns false, if activity has ended. It is
  59                 required that operator() returns false, when
  60                 isActive() returns false. Furthermore, it is required
  61                 that the inactive state is persistent; an activity
  62                 that has become inactive (i.e. isActive() once
  63                 returned false) must stay in that state eternally.
  64             */
  65             virtual bool isActive() const = 0;
  66
  67             /** Notifies the Activity that it has now left the
  68                 ActivitiesQueue
  69
  70                 Use this method to react on the queue removal
  71                 event. For animated shapes, this is e.g. used to
  72                 switch back to the non-sprite presentation mode of the
  73                 shape.
  74              */
  75             virtual void dequeued() = 0;
  76
  77             /** Forces this activity deactivate and get to its end state
  78                 (if possible), but does _not_ dispose.
  79             */
  80             virtual void end() = 0;
  81         };
  82
  83         typedef ::std::shared_ptr< Activity > ActivitySharedPtr;
  84
  85 }
  86
  87 #endif // INCLUDED_SLIDESHOW_SOURCE_INC_ACTIVITY_HXX
  88
  89 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */